This invention relates generally to irrigation sprinklers, and more particularly to irrigation sprinklers of the type having a drive rotor for rotatably driving a spray head through a selected full-circle or part-circle rotary path. More specifically, this invention relates to a conversion adapter for use in quickly and easily converting an irrigation sprinkler from an open case drive rotor to a closed case drive rotor.
Irrigation sprinklers are well known in the art for use in supplying irrigation water over a circular or part-circular ground area around the sprinkler. Typically, such sprinklers employ single or multiple outlet spray nozzles through which the water is ejected upwardly and radially outwardly from a sprinkler case or housing, and include a rotary drive means for rotating the spray nozzle to sweep the stream or streams of irrigation water over the desired terrain area. In many sprinklers, the spray nozzle comprises part of a pop-up mechanism which is designed for pressure responsive movement within the sprinkler case between an elevated position with the spray nozzle above the sprinkler case during normal operation and a retracted position withdrawn substantially within the sprinkler case when the sprinkler is not in operation. In a common installation, the sprinkler case has a lower end thereof connected to an underground water supply line, with the sprinkler case partially buried to position the upper end thereof substantially at ground level.
In the past, impact drive mechanisms have comprised one particularly common form of rotary drive means for an irrigation sprinkler. In an impact drive mechanism, sometimes referred to as an open case drive rotor, an impact drive arm is biased by a spring for oscillatory swinging movement of a deflector into interrupting engagement with the water stream in a manner causing the drive arm to repetitively impact the sprinkler body and thereby drive the sprinkler through a succession of small rotary steps. See, for example, U.S. Pat. No. 4,182,494. Reversal mechanisms are commonly employed to alter the direction of impact drive forces to achieve reversible rotation of the spray head between set end limits of an arcuate part-circle path. However, while impact drive or open case rotor sprinklers have been widely used with highly satisfactory results, the rotary drive and reversing components are necessarily exposed to the elements including sun, wind, precipitation, sand, grit, and the like, wherein such exposure can adversely affect sprinkler operation or result in premature failure. Moreover, such component exposure renders the sprinkler susceptible to vandalism.
In recent years, so-called closed case drive rotor sprinklers have been developed wherein the rotary drive and related reversing mechanisms are substantially enclosed or encased within a closed rotor housing for protection against exposure to the environment and unauthorized tampering. See, for example, U.S. Pat. Nos. 4,253,608 and 4,417,691 which disclose reduction gear trains driven by water turbines for rotatably driving a pop-up spray head of a sprinkler. See also U.S. Pat. Nos. 3,930,628 and 4,625,914 which disclose an impact drive ball arrangement for rotatably driving a pop-up sprinkler spray head. See U.S. Pat. No. 4,681,259 which discloses a reciprocal piston drive device for rotatably driving the sprinkler spray head.
As a result of the enhanced reliability and longevity of closed case drive rotor sprinklers, it is often desirable to upgrade an irrigation system to replace older open case impact drive rotor sprinklers with newer closed case drive rotor sprinklers. Such sprinkler replacement program has required the open case sprinklers to be disassembled from the associated underground water supply line, by disinterring the sprinkler case from the ground. A new closed case rotor sprinkler, including a new sprinkler case, has then been connected to the water supply line and appropriately buried to ground level. This replacement procedure is a costly, time consuming, and labor intensive process. It has not been possible to replace the drive rotor only, while re-using the existing sprinkler case, primarily because the existing sprinkler case is designed to accommodate the oscillatory impact drive arm and thus has a cross sectional size that is too large for a typical closed case drive rotor having a narrower profile.
The present invention relates to a relatively simple conversion adapter for mounting into the sprinkler case of an impact drive sprinkler, following removal of the open case drive rotor, to accommodate quick and easy mounting of a closed case drive rotor into the existing sprinkler case.